const Crypto = require('./crypto.js');

(function () {

  // Shortcut
  var util = Crypto.util;

  Crypto.HMAC = function (hasher, message, key, options) {
    // Allow arbitrary length keys
    key = key.length > hasher._blocksize * 4 ?
      hasher(key, { asBytes: true }) :
      util.stringToBytes(key);

    // XOR keys with pad constants
    var okey = key,
      ikey = key.slice(0);
    for (var i = 0; i < hasher._blocksize * 4; i++) {
      okey[i] ^= 0x5C;
      ikey[i] ^= 0x36;
    }

    var hmacbytes = hasher(util.bytesToString(okey) +
      hasher(util.bytesToString(ikey) + message, { asString: true }),
      { asBytes: true });
    return options && options.asBytes ? hmacbytes :
      options && options.asString ? util.bytesToString(hmacbytes) :
        util.bytesToHex(hmacbytes);

  };

})();

module.exports = Crypto;